Treatment of transparent material



XR' 1549814 SR me e Au 18.1925.

1 UNITED sraresfenrenr o rslcs.

n. or when BOXJBU-BY, 'graasseenosmrsessmnon "fro STATES IBTVEIAJPE Coal- 9AM, oi? szenmermrm, mssema-usmrs, A eonronariox F MAINE- ranarmtnr or 'mansrmmrr K0 Brewing;

light from its surface. The invention is particulariy applicable to'thetreatment of such material as is used for the transparent patches, or panels, ofso-called window envelopes, i. .e., envelopes of the type having an opening therein, over "which is secured a covering of .glassine paper, or othe1ftransparent or semi'transpar'ent material. 2 In window envelopes as thus manufactured, a troublesome feature is the glare or reflection of light from the surface of the transparent patch or anel material, this glare giving rise to ob ection'sjon the part of those required to handle numbers of such e'nrelop'es, as-for instance, in the sorting of mail, particularly when the light strikes the plane of the pateh at a small angle. The present invention aims to treat the surface of the transparent material with a solution which is adapted to leave the surface in a matt, or non-glare condition.

Accordingto my; improved method, an

aqueous solution of calcium chloride" is ltihrushed, or otherwise spread onto one Butface of the transparent material, this solu tion being of high concentration with not w enough water therein to'ca'use warping, or coelzluig, of the transparent material; The

40 evaporation of this solution learesjthe patch auat-erial semen-listless transparent than before, but with a firmly adherent fine do 05% of, calcium'chloricle, the effect of which is to render the surface mutt. Such matt surface is characterized by the fact that it offers no handicap to the attachment of the-patch or panel to the body of the envelope by a-suitaisle adhesive, and furthermore the .umon

of the glare deadening deposit with the.

mama meansut n, 1e24, Serial R0. 731,521.

panel material is zen-complete that the nonglarequelity of the treated su'ria-ce is not impaired by the mechanical handling which a patch onpanel undergoes in a Will-(i037 en- VG O pe machine. In carrying. out my imp-toyed treatment, I have discovered .tlsatit is edvantageous to; add to the calcium "chloride solution, a relatively small amount of a salt,ylilre sodium or potassium acetate- When such a salt is in-' eluded the treatin solution, any flGRdlr tron which might ten to liberate acid in the deposit on the panel material will result in the liberat on of an acid not destructive to 'ccllulose, Instead ofthe hydrochloric acid wh ch might he liberated from the calcium chloride solution alone. While sodium or "potassium acetate is s ecifically :tnentiojn'ecl as the salt added to t e solution, it is obvious that other salts may be em lo ed which are capable of reacting with rochloric acid so as to yield an acid.- not (lestrueti-ve to'the patch material.

From'the foregoing, itis' upper-e that by the raetice of my invention, patch materialeen e renderefi'matt or .gl'areles's without too much-reducing its transparency, and

without impairing the qualities which are essential for its successful hand-ling by an envelope making machine; I claim-- 1. The treatment oat-transparent material by a'p flying to the surface thereof a solution )0; calcium chloride which on evaporation leaves a ,tleposit giving a substantially .85

matt surface. Y

2, The treatment of transparent material by applying to the-surface tl-lQiTQOf a concentrated. aqueous solx-xtion of calcium chloride which on evaporation leaves said in-aterial t-ra-nsparent with a substantially glare: less surface. a 4

3, The herein described treatment of transparent material with a strong solution of calcium chloride containing e salt capable of reacting with hydroehlorie acid sons to yield an acid not'de'struc'tive to the said Ina-.-

terial. 4

" S'W-ETT.

. in a 

